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Journal of Biomaterials Applications Aug 2022Ultra-high molecular weight polyethylene (UHMWPE) and its derivatives have been clinically used as an acetabular liner material in total hip joint replacement (THR) over...
Ultra-high molecular weight polyethylene (UHMWPE) and its derivatives have been clinically used as an acetabular liner material in total hip joint replacement (THR) over last six decades. Despite significant efforts, the longevity of UHMWPE implants is still impaired due to their compromised tribological performance, leading to osteolysis and aseptic loosening. The present study aims to critically evaluate and analyze the tribological performance, of the next generation acetabular liner material, that is, a chemically modified graphene oxide (GO) reinforced HDPE/UHMWPE (HU) bionanocomposite (HUmGO), against stainless steel (SS 316L) counterface in lubricated conditions. This work also provides a performance comparative assessment of HUmGO with respect to medical grades, UHMWPE (UC) and crosslinked UHMWPE (XL-UC). Significant attempts have been made to correlate the tribological properties (frictional behavior, wear rate, wear debris shape and size, wear mechanism) with the physicomechanical conditions (contact stresses) at sliding contact and the variation in molecular architecture of different UHMWPE materials. Additionally, an emphasis is put forward to critically anlyze the nature of lubrication regime based on the bearing characterstic parameters. HUmGO exhibited a lower COF (0.07) and specific wear rate (2.86 × 10mm/Nm) than UC and XL-UC under identical sliding conditions. The worn surfaces on HUmGO revealed the signatures of less abrasive wear and limited deformation. Based on the estimated lambda (λ) ratio and Sommerfield number, all the investigated sliding contacts exhibited boundary lubrication. Taken together, the modified GO reinforced HDPE/UHMWPE bionanocomposite can be considered as a new generation biomaterial for the fabrication of acetabular liner for hip-joint prosthesis
Topics: Hip Prosthesis; Humans; Materials Testing; Polyethylene; Polyethylenes; Prosthesis Failure; Surface Properties
PubMed: 35502987
DOI: 10.1177/08853282221085633 -
Environmental Science & Technology May 2024The slow reaction rates to chemical and photochemical degradation are well-known properties of plastics. However, large plastic surfaces exposed to environmental...
The slow reaction rates to chemical and photochemical degradation are well-known properties of plastics. However, large plastic surfaces exposed to environmental conditions release particles and compounds that affect ecosystems and human health. The aim of this work was to identify compounds associated with the degradation of polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) microplastics (markers) on silica and sand and evaluate their use to screen microplastics on natural sand. Products were identified by using targeted and untargeted LC-HRMS analysis. All polymers underwent chemical oxidation on silica. PE released dicarboxylic acids (HOC-(CH)-COH ( = 4-30), while PS released /-chalcone, -dypnone, 3-phenylpropiophenone, and dibenzoylmethane. PVC released dicarboxylic acids and aromatic compounds. Upon irradiation, PE was stable while PS released the same compounds as under chemical oxidation but at lower yields. Under the above condition, PVC generated HOC-[CH-CHCl]-CH-COH and HOC-[CH-CHCl]-COH ( = 2-19) dicarboxylic acids. The same products were detected on sand but at a lower concentration than on silica due to better retention within the pores. Detection of markers of PE and PS on natural sand allowed us to screen microplastics by following a targeted analysis. Markers of PVC were not detected before or after thermal/photo-oxidation due to the low release of compounds and limitations associated with surface exposure/penetration of radiation.
Topics: Microplastics; Plastics; Polyethylene; Environmental Monitoring; Environmental Biomarkers
PubMed: 38685194
DOI: 10.1021/acs.est.3c09662 -
Environment International Aug 2022The effects of microalgal biofouling on microplastic (MP) may differ from bacterial biofouling. In this study, the influence of microalgae on MP surface alteration,...
The effects of microalgal biofouling on microplastic (MP) may differ from bacterial biofouling. In this study, the influence of microalgae on MP surface alteration, structural change, and adsorption of organic micropollutants was evaluated. Virgin polyethylene (PE), polyvinyl chloride (PVC), and polyamide (PA) were each immersed in algal photobioreactor and river freshwater for 30 days to simulate algal and river microbe biofouling respectively. Consequently, their physicochemical changes and adsorption potential of a mixture of six bisphenol analogues (BPA, BPS, BPE, BPB, BPF, BPAF) and two parabens (propyl-paraben, benzyl-paraben) were investigated. Owing to the algal bioactive compounds, major microalgae-induced biofouling and more MP aging than the river microbe aging were observed through fractures, pits, cracks, and algal attachments. Intrusion of algal organic matter and scission of polymeric functional groups were revealed during microalgal immersion and the potential MP aging pathways were proposed. Algal biofouling considerably altered the intrinsic properties of the MPs, consequently the adsorption capacity of PE and PVC was enhanced by 3.04-6.72 and 2.14-8.72 times, respectively. Adsorption process onto algal-aged MPs was pH-dependent, endothermic, non-spontaneous, and favored by hydrogen bonds. Meanwhile, the amide group in PA structure was conducive to organic micropollutant adsorption, which was likely reduced by algal aging and the erosion of the N-H stretching. Moreover, higher adsorption capacities of organic micropollutants were shown by the algal-biofilm PE and PVC than virgin and river microbial biofilm MPs. This study discloses that, biofouling and aging of MPs by microalgae through their bioactive components would engender more incidences on MP properties, organic micropollutants adsorption with associated environmental and health hazards.
Topics: Microplastics; Plastics; Parabens; Microalgae; Adsorption; Polyethylene; Water Pollutants, Chemical
PubMed: 35803076
DOI: 10.1016/j.envint.2022.107382 -
The Science of the Total Environment Jan 2023Forty-eight tropical shallow lakes (depth ≤ 4 m) across a climatic gradient were assessed for microplastic (MPs; <5 mm) pollution based on MPs concentrations in...
Forty-eight tropical shallow lakes (depth ≤ 4 m) across a climatic gradient were assessed for microplastic (MPs; <5 mm) pollution based on MPs concentrations in archive samples from lake shore sediments. The MPs were classified by type (fragments or fibres), colour (yellow, black, red, green, blue, white, and transparent), size (0.55 to 4.93 mm), and polymer (polyester, polyethylene, chlorinated polyethylene, and polyamide). Sediments were predominantly medium sand, and all samples (144) contained MPs, consisting of 24 % fragments (6.3 ± 11.3 MPs·300 g) and 76 % fibres (21.25 ± 12.7 MPs·300 g). The lake climate (humid, transitional, or semi-arid), type of surrounding land use (urban, semi-arid, or rural), and distance from the shoreline (0, 5 or 10 m) did not explain the differences in MPs concentrations, partially refuting the initial hypothesis. The only significant difference was between the sample medians for the number of fragments based on the region (H = 7.586; p = 0.0481). The number of fragments in the lakes in the humid region was greater than that in the semi-arid region (p < 0.05). Poor sanitation, sewage effluents, and solid wastes reaching and accumulating in the lakes may be the primary and transversal conditioning factors for this small difference among diverse environments. Freshwater lakes are investigated in all continents, and the present study contributes to the first record of MPs in shallow lake sediments in eastern South America. The 48 shallow lakes assessed showed a relatively low concentration of MPs compared to other lake contaminants reported in the international literature. This information coincides with public policies issued, regarding the control and reduction of plastics and MPs in Brazil, and the study region.
Topics: Microplastics; Lakes; Plastics; Geologic Sediments; Environmental Monitoring; Water Pollutants, Chemical; Polyethylene; Brazil
PubMed: 36099957
DOI: 10.1016/j.scitotenv.2022.158671 -
Environmental Monitoring and Assessment Feb 2023In the present work, the potential of Cephalosporium strain in degrading the pre-treated (ultraviolet irradiation followed by nitric acid treatment) low-density...
In the present work, the potential of Cephalosporium strain in degrading the pre-treated (ultraviolet irradiation followed by nitric acid treatment) low-density polyethylene and high-density polyethylene films was investigated. Our observations revealed a significant weight reduction of 24.53 ± 0.73% and 18.22 ± 0.31% in pre-treated low-density polyethylene and high-density polyethylene films respectively, after 56 days of incubation with the Cephalosporium strain. Changes in the physicochemical properties of the mineral salt medium (MSM) were studied to assess the extent of biodegradation. The pH of the MSM decreased gradually during the incubation period, whereas its total dissolved solids and conductivity values increased steadily. Fourier transform infrared spectroscopy (FTIR) indicated the formation of hydroxyl and C = C groups in biodegraded low-density polyethylene films, while in the case of biodegraded high-density polyethylene films it indicated the [Formula: see text]CH stretching. Furthermore, the thermogravimetric analysis (TGA) revealed an enhancement in the thermal stabilities of both the LDPE and HDPE films post the biodegradation. Modifications in the polymer surface morphologies after UV irradiation, chemical treatment, and biodegradation steps were visualized via scanning electron microscopy (SEM) analysis. All our observations confirm the ability of the Cephalosporium strain in biodegrading the pre-treated LDPE and HDPE films.
Topics: Polyethylene; Acremonium; Environmental Monitoring; Biodegradation, Environmental; Spectroscopy, Fourier Transform Infrared
PubMed: 36780023
DOI: 10.1007/s10661-023-10982-8 -
Journal of the Mechanical Behavior of... Mar 2022A novel polymer-on-metal hip joint prosthesis design that makes use of uni-directional articulations was developed and tested in this work. The new implant was tested...
A novel polymer-on-metal hip joint prosthesis design that makes use of uni-directional articulations was developed and tested in this work. The new implant was tested using two polymer variants, virgin ultra-high molecular weight polyethylene (UHMWPE), and Vitamin E-infused highly crosslinked polyethylene (VEHXPE). The degrees of freedom of the ball-and-socket are reproduced by three cylindrical orthogonally-aligned articulations. This unconventional design leverages on the molecular orientation hardening mechanisms of the polyethylene and increased contact area to minimize wear. An experimental hip joint simulator was used to compare the gravimetric wear of the conventional ball-on-socket and the new implant. The new prosthesis including UHMWPE components produced a 78% reduction in wear, whereas the new prosthesis with VEHXPE components produced a 100% reduction in wear, as no measurable wear was detected. Machining marks on the acetabular cups of the new prosthesis were retained for both polyethylene variants, further demonstrating the low levels of wear exhibited by the new implants. Both polyethylene materials produced particles in the range of 0.1-1.0 μm, which are the most biologically active. Nonetheless, the extremely low wear rates are likely to induce minimal osteolysis effects. Furthermore, the novel design also offers an increase of more than 24% in the range of motion in flexion/extension when compared to a dual-mobility hip implant. A prototype of the prosthesis was implanted into a Thiel-embalmed human cadaver during a mock-surgery, which demonstrated high resistance to dislocation and the possibility of performing a figure of four position.
Topics: Acetabulum; Arthroplasty, Replacement, Hip; Hip Joint; Hip Prosthesis; Humans; Materials Testing; Polyethylene; Polyethylenes; Prosthesis Design; Prosthesis Failure; Vitamin E
PubMed: 35033983
DOI: 10.1016/j.jmbbm.2021.105072 -
Nursing in Critical Care Jul 2021Exposure keratopathy may lead to serious complications such as microbial keratitis, corneal perforation, and visual impairment if not treated. (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Exposure keratopathy may lead to serious complications such as microbial keratitis, corneal perforation, and visual impairment if not treated.
AIM
To compare the effect of carbomer eye drops when used alone and in combination with polyethylene covers in the healing of exposure keratopathy.
METHODS
A single blind randomized-controlled trial (RCT) in two intensive care units (ICUs) was carried out in a university hospital in Western Turkey between September 2011 and December 2012. The control group received only carbomer, eye drops while the intervention group received both carbomer eye drops and polyethylene covers. The primary outcome was the decrease or absence of corneal damage, which refers to healing. Corneal damage was followed up with a fluorescein dye test (decrease/absence of the corneal staining) by the same ophthalmologist for 10 days.
RESULTS
A total of 43 corneas in 24 patients were studied. Corneal epithelial defects decreased in the intervention group by day 2 and progressed or remained unchanged in the control group every day (P = .001). Patient characteristics did not affect the grade ranges of corneal staining in the groups except for level of consciousness.
CONCLUSION
Carbomer eye drops, when used in combination with polyethylene covers, were effective in managing exposure keratopathy.
RELEVANCE TO CLINICAL PRACTICE
Corneal damage and further ocular complications can be reduced with the utilization of polyethylene covers in nursing care and treatment.
Topics: Humans; Intensive Care Units; Polyethylene; Turkey
PubMed: 32830416
DOI: 10.1111/nicc.12542 -
Environmental Microbiology Jun 2024Plastic pollution is a vast and increasing problem that has permeated the environment, affecting all aspects of the global food web. Plastics and microplastics have...
Plastic pollution is a vast and increasing problem that has permeated the environment, affecting all aspects of the global food web. Plastics and microplastics have spread to soil, water bodies, and even the atmosphere due to decades of use in a wide range of applications. Plastics include a variety of materials with different properties and chemical characteristics, with polyethylene being a dominant fraction. Polyethylene is also an extremely persistent compound with slow rates of photodegradation or biodegradation. In this study, we developed a method to isolate communities of microbes capable of biodegrading a polyethylene surrogate. This method allows us to study potential polyethylene degradation over much shorter time periods. Using this method, we enriched several communities of microbes that can degrade the polyethylene surrogate within weeks. We also identified specific bacterial strains with a higher propensity to degrade compounds similar to polyethylene. We provide a description of the method, the variability and efficacy of four different communities, and key strains from these communities. This method should serve as a straightforward and adaptable tool for studying polyethylene biodegradation.
Topics: Polyethylene; Biodegradation, Environmental; Bacteria; Microbiota; Soil Microbiology
PubMed: 38843592
DOI: 10.1111/1462-2920.16658 -
Journal of Hazardous Materials Oct 2023Polyethylene (PE) is a widely used plastic known for its resistance to biodegradation, posing a significant environmental challenge. Recent advances have shed light on...
Polyethylene (PE) is a widely used plastic known for its resistance to biodegradation, posing a significant environmental challenge. Recent advances have shed light on microorganisms and insects capable of breaking down PE and identified potential PE-degrading enzymes (PEases), hinting at the possibility of PE biorecycling. Research on enzymatic PE degradation is still in its early stages, especially compared to the progress made with polyethylene terephthalate (PET). While PET hydrolases have been extensively studied and engineered for improved performance, even the products of PEases remain mostly undefined. This Perspective analyzes the current state of enzymatic PE degradation research, highlighting obstacles in the search for bona fide PEases and suggesting areas for future exploration. A critical challenge impeding progress in this field stems from the inert nature of the C-C and C-H bonds of PE. Furthermore, breaking down PE into small molecules using only one monofunctional enzyme is theoretically impossible. Overcoming these obstacles requires identifying enzymatic pathways, which can be facilitated using emerging technologies like omics, structure-based design, and computer-assisted engineering of enzymes. Understanding the mechanisms underlying PE enzymatic biodegradation is crucial for research progress and for identifying potential solutions to the global plastic pollution crisis.
Topics: Polyethylene; Polyethylene Terephthalates; Biodegradation, Environmental; Hydrolases
PubMed: 37690195
DOI: 10.1016/j.jhazmat.2023.132449 -
Scientific Reports Jun 2023A variety of biosensors have been proposed to quickly detect and measure the properties of individual microorganisms among heterogeneous populations, but challenges...
A variety of biosensors have been proposed to quickly detect and measure the properties of individual microorganisms among heterogeneous populations, but challenges related to cost, portability, stability, sensitivity, and power consumption limit their applicability. This study proposes a portable microfluidic device based on impedance flow-cytometry and electrical impedance spectroscopy that can detect and quantify the size of microparticles larger than 45 µm, such as algae and microplastics. The system is low cost ($300), portable (5 cm [Formula: see text] 5 cm), low-power (1.2 W), and easily fabricated utilizing a 3D-printer and industrial printed circuit board technology. The main novelty we demonstrate is the use of square wave excitation signal for impedance measurements with quadrature phase-sensitive detectors. A linked algorithm removes the errors associated to higher order harmonics. After validating the performance of the device for complex impedance models, we used it to detect and differentiate between polyethylene microbeads of sizes between 63 and 83 µm, and buccal cells between 45 and 70 µm. A precision of 3% is reported for the measured impedance and a minimum size of 45 µm is reported for the particle characterization.
Topics: Electric Impedance; Mouth Mucosa; Plastics; Microspheres; Polyethylene
PubMed: 37386229
DOI: 10.1038/s41598-023-37506-1